If a hearing impaired user is wearing a left and a right hearing aid, it is often desired that the hearing aids operate in a somehow synchronized manner. The questions are: how much synchronization is desired, what type of synchronization is desired and in which circumstances does one need which type of synchronization. A complicating issue is that it may be difficult to predefine the desired synchronization after a fitting session, since preferences concerning the symmetry of the binaural hearing aid system may be depending on environment, may be changing throughout the usage period, or may simply be hard to predefine based on a laboratory fitting procedure.
A recent study, published as “Online Personalization of Hearing Instruments,” EURASIP Journal on Audio, Speech, and Music Processing, vol. 2008, Article ID 183456, 14 pages, 2008. doi:10.115512008/183456, by Alexander Ypma, Job Geurts, Serkan Özer, Erik van der Werf, and Bert de Vries, where a group of 10 hearing impaired users were asked to personalize a noise reduction parameter on both instruments revealed that some participants had a preference to asymmetry in the binaural hearing aid system.
Currently in order to configure a binaural hearing aid system a user need to adjust both the left and the right hearing aid Individually. This two-sided user Interaction with the hearing aid system is contemplated to be a burden on the user.
Left and right hearing aids may communicate with each other, e.g. via a wireless link between the hearing aids. With such a configuration one could use the combined knowledge on symmetric and asymmetric left-right preferences by synchronizing the hearing aids in an asymmetric way, i.e. benefit from the ease of synchronization, but at the same time allowing asymmetric preferences.
Additionally, a model for asymmetric hearing loss and/or preferences may be used for predicting asymmetric parameter changes. Furthermore, user adjustments to one of the hearing aids could be used to infer adjustments to the other instrument in the binaural hearing aid system or even to update the settings of the binaural hearing aid system based on only partial (left- or right instrument) input.
A first aspect of present embodiments provides a method of adjusting a signal processing parameter for a first and a second hearing aid forming part of a binaural hearing aid system to be worn by a user, the binaural hearing aid system comprising a user specific model representing a desired asymmetry between the first ear and the second ear of the user is provided, the method comprising the steps of:                detecting a request for processing parameter change at the first hearing aid,        adjusting the signal processing parameter in the first hearing aid,        adjusting a processing parameter for the second hearing aid based on the request for processing parameter change and the user specific model        
The step of detecting may include recording a signal or request for change of parameter, e.g. via a hardware interrupt or other signaling means.
When a person operates one of the hearing aids via some control, e.g. an actuator such as a control wheel (e.g. a volume wheel), a push button, a toggle switch or some remote device that controls the hearing aid, the method according to the present embodiments synchronizes the other hearing aid with the first hearing aid, but preferably not by simply copying the same adjustment to the other hearing aid. The method according to the present embodiments ensures that differences in preferences and hearing loss in the two ears are taken into account. The model may be based on measurements by e.g. audiogram or some derivative thereof like PTA. PTA is pure tone average i.e. the average of pure tone hearing thresholds at e.g. 500, 1000, and 2000 Hz.
The role of a first and a second hearing aid may be played interchangeably by both the left and right hearing aid in a binaural hearing aid system.
The model used in the method according to the first aspect may be a frequency dependent model. This may be advantageous as hearing loss may not be uniform in the entire frequency spectrum or over a given frequency interval.
It is understood that the term hearing loss may be construed to mean hearing loss in the first and/or second ear. In other embodiments the term hearing loss may be construed to mean the difference in the hearing losses between the first and second ear and may possibly also include other type of data that e.g. may reflect any desired asymmetry.
In the method according to the present embodiments, a request for change of processing parameter is detected. The request may originate from one of several events or a combination of events, including but not limited to operation of a wheel on one of the hearing aids, a push-button on one of the hearing aids, operation of a remote control controlling or communicating with one or both of the hearing aids, a device monitoring ambient sound or any combinations hereof.
The request is processed and the corresponding parameter, or parameters, is adjusted in the first hearing aid. A corresponding adjustment of the second hearing aid is calculated, predicted or determined on the basis of the request and by using a model or rule representing the hearing loss and/or preferences of the second ear. The processing parameter for the second hearing aid is then adjusted accordingly.
The method according to the present embodiments make use of prior knowledge on the hearing loss in each ear and other audiological or psychophysical prior knowledge and environmental information in doing the synchronized adjustment in an asymmetric manner.
It is an advantage that the signal processing parameter in the first hearing aid may be adjusted based on the request for processing parameter change and further by using a further specific model representing the hearing loss of the first ear of the wearer. This allow adjustment of the hearing aid processing parameter of the first hearing aid to be adjusted using a model or rule representing the hearing loss both in the first ear as well as in the second ear. When synchronizing the level of steering parameters an advantage is that constraining identical steering parameters on both sides of the hearing aid system can still be looked upon as asymmetric synchronization. This is because asymmetry between left and right hearing aid parameters may be caused by different acoustic fields at the two ears. Steering parameters are parameters that govern the computation of hearing aid processing parameters from environmental descriptors like sound features or sound classification outputs. Steering parameters may also be parameters that relate sound environment to hearing aid processing parameters. These may not be fixed to a certain value. The steering parameters may furthermore be modifiable in such a way that the values of the hearing aid parameter(s) in a certain environment reflect the user preference as good as possible
Also, the user has to operate only one of the hearing aids, whereas both hearing aids are adjusted in a manner that is tailored to the left and right hearing loss.
As mentioned above, the request for processing parameter change may originate from a wearer initiated operation of an actuator or may be generated in response to changes in signal characteristics. The hearing aid may include the possibility to detect the ambient sound environment to detect present sound environment conditions, such as noisy conditions e.g. due to wind noise or noise originating from surrounding speech or other ambient noise sources.
In some embodiments the processing parameter may be volume level, but other parameters may be used, such as equalizing parameters, sound classification parameters, noise reduction parameters, noise reduction, compression ratio, time constants, parameters of classifier module, beamforming (directional processing) parameters, feedback suppression parameters, dynamic range compression parameters and the like. Furthermore, hyperparameters may be controlled or changed. A hyperparameter is not a hearing aid processing parameter as such. It is a parameter that governs the working of a processing algorithm, and is typically fixed to a certain value.
It is a particular advantage of some embodiments that the model may be adapted in response to the request for processing parameter change. If a user or wearer is subjected to a particular environment situation and adjusts the hearing aid accordingly the model or rule may be adjusted or modified in response to that change request. This is contemplated to reduce the number of times a wearer needs to adjust a hearing aid, thereby possibly increasing the wearer satisfaction with the hearing aid.
It is further advantageous that the method according to the present embodiments provides the possibility that the request for processing parameter change may comprise information regarding one or more processing parameters to be changed and a parameter representing an amount of change. The request may comprise information regarding which parameter or parameters to change as well as the amount of change of that parameter or parameters, e.g. an amount of increase or decrease of volume.
In one embodiment the first hearing aid may be a master device and the second hearing aid may be a slave device. This allows a user to make a change at the first, master, hearing aid alone and the change will then be transferred or imposed on the second, slave, device. It is further possible that both hearing aids may assume the role of the master device, but not at the same time, in the meaning that both devices may receive change requests and subsequently transfer or apply the change to the other device.
In one advantageous embodiment, the model may comprise two separate steering vectors each associated with a hearing loss in the first and second ear of the user, respectively, which steering vectors are coupled by a probability model representing the combined binaural system.
In another advantageous embodiment of the method according to the first aspect the overall degree of asymmetry may further depend on the difference between microphone recordings in the first and second hearing aid.
According to some embodiments, the model representing the hearing loss of the user may comprise a measured or estimated hearing loss in the first and/or second ear of the user. This may be advantageous when hearing loss is not identical in the two ears.
In a still further advantageous embodiment, the request for processing parameter change may originate from a user initiated operation of an actuator or is generated in response to changes in signal characteristics. The request may e.g. originate from a volume wheel or other interaction means operated by a user.
In some embodiments, the method according to the first aspect not performed in a fitting situation. The fitting situation is usually performed by a technician e.g. at a laboratory or clinic. The method according to the present embodiments is preferably in use while the wearer is in any situation any other person would be, e.g. work, leisure situations such as dinners at restaurants, also larger groups of people gathered.
The method is preferably implemented in a hearing aid to be used by a wearer in any noisy situation where hearing impaired persons otherwise would feel discomfort without the hearing aid.
The request may be based on a vector of parameters. The models of the first and the second hearing aid may be a shared or common parameter or parameter set or vector.
A second aspect relates to a hearing aid comprising a signal processor, wherein the hearing aid is adapted for forming part of a binaural hearing aid system during use and for receiving information from another hearing aid that during use also is adapted to form part of the binaural hearing aid system, wherein the signal processor is configured to adjust a signal processing parameter in the hearing aid based on a request for a processing parameter change in the other hearing aid and a specific model representing a hearing loss of a user.
The hearing aid according to the second aspect may further be configured or adapted to perform any of the steps mentioned in relation to the method according to the first aspect of the embodiments.
The model may be placed in the first hearing aid or it may be placed in the second hearing aid. The model may however in an alternative embodiment be placed in a third device, such as a remote control, a personal portable device such as a body worn device or a PDA, Personal Data Assistant, a mobile/cellular phone or the like.
In an embodiment, the model may be shared between the first and the second hearing aid in such a way that some parts of the model are placed in the first hearing aid and some parts are placed in the second hearing aid. For example in one embodiment those parts of the model that relate to the hearing loss in the ear that is to be compensated with the first hearing aid are placed in the first hearing aid, while those parts of the model that relate to the hearing loss in the ear that is to be compensated by the second hearing aid are placed in the second hearing aid.
In another embodiment these parts of the model may be overlapping, and in some embodiments be totally overlapping, i.e. the first and the second hearing aid may both be equipped with the same model in the case of extreme overlap.
In accordance with some embodiments, a method of adjusting a signal processing parameter for a first hearing aid and a second hearing aid forming parts of a binaural hearing aid system to be worn by a user is provided. The binaural hearing aid system comprises a user specific model representing a desired asymmetry between a first ear and a second ear of the user. The method includes detecting a request for processing a parameter change at the first hearing aid, adjusting the signal processing parameter in the first hearing aid, and adjusting a processing parameter for the second hearing aid based on the request for processing parameter change and the user specific model.
In accordance with other embodiments, a hearing aid includes a signal processor, wherein the hearing aid is configured for forming a part of a binaural hearing aid system and for receiving information from an other hearing aid that is also configured to form a part of the binaural hearing aid system, wherein the signal processor is configured to adjust a signal processing parameter in the hearing aid based on a request for a processing parameter change in the other hearing aid and a specific model representing a hearing loss of a user.